The colour of aquatic plants found deep under oceans?

Question

I have read that many aquatic plants found in deep oceans are red in colour, however, I do not understand why. As red is the color which gets the least scattered it should be the only light available to them. Thus reflecting red light would deprive them of any light. Yet they appear to be in red color. Why is this so?

Answer 1

The blue and green colors reach up to 200 m inside water, while all the other colors including violet can reach only up to the first 100 m inside the oceans. Since light has a difficult time penetrating into the oceans, phycobiliproteins make this job easier by absorbing whatever light is available; they absorb the green portion of the light and turn it to red light, which is the color of light required by Chl